You cannot fileOut or printOut the (method) category "fileIn/Out"
because the way the filename is cunstructed it would contain a
slash. The same problem exists for class categories but I am not aware
of any class category that contains a slash. You cannot create a class
or a method with a slash in it so there's not problem.

Funny enough the problem is located in the methods
fileOutCategory:asHtml: (in SystemOrganizer and ClassDescription)
which belong to the category "fileIn/Out".

You can also call a changeSet "fileIn/Out". It will create a file
Out.1.cs. Not too bad.

I am not sure what to do next in terms of bug reporting/fixing.